Surd Calculations?

Surds are numbers left in 'square root form' (or 'cube root form' etc). They are therefore irrational numbers. Surds are the root of numbers and not whole numbers.

Multiplication

square root of ab = square root of a x square root of b

square root of a x square root of a = a

Example: 

√2 × √6 = √12 (= 2× 6)

= √4 × √3

= 2√3

Addition and Subtraction

4√3 - 2√3 = 2√3

5√5 + 8√5 = 13√5

Note: 5√7 + 3√3 cannot be manipulated because the surds are different (one is √7 and one is √3)

Example:

Simplify √12 + √27

12 = 3 × 4. So √12 = √(3 × 4) = √3 × √4 = 2 × √3.

Similarly, √27 = 3√3.

Hence √12 + √27 = 2√3 + 3√3 = 5√3

 

 

 

NB
Answered by Nita B. Maths tutor

11001 Views

See similar Maths GCSE tutors

Related Maths GCSE answers

All answers ▸

solve the simultaneous equation: 8x+2y=46; 7x+3y=47


How do I find out where two functions meet on a graph?


How do I multiply two brackets without missing terms when multiplying?


A is the point (4,1). B is the point (10,15). Find the perpendicular bisector or of AB.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

© MyTutorWeb Ltd 2013–2025

Terms & Conditions|Privacy Policy
Cookie Preferences